Oxidation of soot in gasoline exhaust on Mn2O3 catalyst

A Mn2O3 catalyst was investigated for soot oxidation in gasoline exhaust. Catalytic studies performed in model exhaust with Mn2O3/soot mixtures in tight contact showed efficient soot oxidation above 250 degrees C. This high performance was additionally confirmed on a gasoline engine test bench using a Mn2O3-coated particulate filter. The mechanism of the oxygen transport from the gas phase to soot was investigated by kinetic modeling of O2 adsorption and desorption as well as catalytic studies using 18O2. As a result, it was suggested that O2 dissociatively adsorbs on Mn2O3 followed by surface migration and transfer of oxygen to the soot at physical contact points between the two solids. The surface, sub-surface and bulk oxygen of the catalyst were also found to play a role. Enhanced participation of bulk oxygen appeared with declining O2 content due to partial reduction of Mn2O3 and formation of oxygen vacancies driving the oxygen mobility.

Automated summary

A Mn2O3 catalyst was found to exhibit efficient soot oxidation in gasoline exhaust, both in model exhaust with Mn2O3/soot mixtures and in a gasoline engine test bench with Mn2O3-coated particulate filter. The mechanism of oxygen transport from gas phase to soot was investigated, suggesting dissociative adsorption and surface migration of O2 on Mn2O3, followed by transfer of oxygen to soot at physical contact points. The role of surface, sub-surface, and bulk oxygen in the catalyst was also observed, with enhanced participation of bulk oxygen due to declining O2 content.